How to use a LED

Abstract

LED - Light Emiting Diode
I always have the same problem: what connector of the LED is to be connected with ground and which one with the positive voltage? If you are not able to remind this (like me) look at the picture below. Where C is the cathode and A the anode.

Figure 1: Connecting Schema
Figure 1: Connecting Schema

Which Resistor Value?

The current applied to a LED should be within 10m[A] and 20m[A].
One quality of the LED is that it always has a typical voltage drop of about 2.2[V] (depends on the colour). In the typical hobbyist's computer environment we deal with 5[V]. So if you connect a LED like shown in the picture above you will have a 'rest' of 2.8[V]. With Ohm's law you will have resistor values from 140[Ohm] up to 280[Ohm] suitable to be used as multiplier to limitate the current to 10m[A]-20m[A].


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this page was updated: 04.01.02 14:20:47
holger@zahnleiter.org

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